Remove keyValidationClass after cherry pick
since it was not available in 0.7
Conflicts:
core/src/main/java/me/prettyprint/cassandra/model/BasicColumnFamilyDefinition.java
core/src/main/java/me/prettyprint/cassandra/service/ThriftCfDef.java
core/src/main/java/me/prettyprint/hector/api/ddl/ColumnFamilyDefinition.java